system32\cmd.exe problem - help please

Hi there, hope one of you chaps can help this computer numpty fix his PC.

Booted up pc and get a consitently flashing at high speed window that moves part way across screen and seems to work its way on top of everything. Only able to type this by minimising then maximising window.

The problem window is titled c:\windows\system32\cmd.exeThe text within the rapidly flickering window reads:-access deniedthe system cannot find the path specified

The tool bar has atiny little black box that continually moves left to right with what looks like a command prompt in it.

Any help resolving this will of course be extreeeeemly appreciated. Thanks